Added thread variable max_seeks_for_key
Change optimizer to prefer key lookups before table scan Change table scans to be done after tables with constrains on scanned table
This commit is contained in:
parent
5f556f11e0
commit
34919a03c4
@ -161,7 +161,7 @@ SELECT DISTINCT UserId FROM t1 WHERE UserId=22;
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UserId
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drop table t1;
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CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
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INSERT INTO t1 VALUES (1,1),(2,1);
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INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
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CREATE TABLE t2 (a int(10) unsigned not null, key (A));
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INSERT INTO t2 VALUES (1),(2);
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CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
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@ -189,7 +189,7 @@ insert into t4 select * from t3;
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insert into t3 select * from t4;
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explain select distinct t1.a from t1,t3 where t1.a=t3.a;
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table type possible_keys key key_len ref rows Extra
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t1 index PRIMARY PRIMARY 4 NULL 2 Using index; Using temporary
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t1 index PRIMARY PRIMARY 4 NULL 4 Using index; Using temporary
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t3 ref a a 5 t1.a 10 Using where; Using index; Distinct
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select distinct t1.a from t1,t3 where t1.a=t3.a;
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a
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@ -200,16 +200,16 @@ select distinct 1 from t1,t3 where t1.a=t3.a;
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1
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explain SELECT distinct t1.a from t1;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct t1.a from t1 order by a desc;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT t1.a from t1 group by a order by a desc;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct t1.a from t1 order by a desc limit 1;
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table type possible_keys key key_len ref rows Extra
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t1 index NULL PRIMARY 4 NULL 2 Using index
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t1 index NULL PRIMARY 4 NULL 4 Using index
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explain SELECT distinct a from t3 order by a desc limit 2;
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table type possible_keys key key_len ref rows Extra
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t3 index NULL a 5 NULL 204 Using index
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@ -534,11 +534,11 @@ a b
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explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b;
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table type possible_keys key key_len ref rows Extra
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t1 ALL NULL NULL NULL NULL 6 Using temporary; Using filesort
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t2 ALL a NULL NULL NULL 4 Using where
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t2 ALL a NULL NULL NULL 3 Using where
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explain select t1.a,t2.b from t1,t2 where t1.a=t2.a group by t1.a,t2.b ORDER BY NULL;
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table type possible_keys key key_len ref rows Extra
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t1 ALL NULL NULL NULL NULL 6 Using temporary
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t2 ALL a NULL NULL NULL 4 Using where
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t2 ALL a NULL NULL NULL 3 Using where
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drop table t1,t2;
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create table t1 (a int, b int);
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insert into t1 values (1, 4),(10, 40),(1, 4),(10, 43),(1, 4),(10, 41),(1, 4),(10, 43),(1, 4);
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@ -166,7 +166,7 @@ alter table t1 add column new_col char(1) not null, add key (btn,new_col), drop
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update t1 set new_col=btn;
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explain select * from t1 where btn="a";
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table type possible_keys key key_len ref rows Extra
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t1 ALL btn NULL NULL NULL 14 Using where
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t1 ALL btn NULL NULL NULL 11 Using where
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explain select * from t1 where btn="a" and new_col="a";
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table type possible_keys key key_len ref rows Extra
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t1 ref btn btn 11 const,const 10 Using where
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@ -104,9 +104,7 @@ KEY category (category,county,state)
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INSERT INTO t2 VALUES (3,2,11,12,5400,7800);
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INSERT INTO t2 VALUES (4,2,25,12,6500,11200);
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INSERT INTO t2 VALUES (5,1,37,6,10000,12000);
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select a.id, b.category as catid, b.state as stateid, b.county as
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countyid from t1 a, t2 b where (a.token =
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'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
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select a.id, b.category as catid, b.state as stateid, b.county as countyid from t1 a, t2 b ignore index (primary) where (a.token ='a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
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id catid stateid countyid
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27 2 12 11
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28 2 12 11
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@ -36,7 +36,7 @@ a a a a
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explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B;
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table type possible_keys key key_len ref rows Extra
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t1 ALL a NULL NULL NULL 5
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t2 ALL b NULL NULL NULL 5 Using where
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t2 ALL b NULL NULL NULL 4 Using where
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select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B order by binary t1.a,t2.a;
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a b a b
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A B a a
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@ -335,12 +335,12 @@ t1 1 c_2 1 c A 5 NULL NULL YES BTREE
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t1 1 c_2 2 a A 5 NULL NULL BTREE
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explain select * from t1,t2 where t1.a=t2.a;
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table type possible_keys key key_len ref rows Extra
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t1 ALL a NULL NULL NULL 5
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t2 ALL a NULL NULL NULL 2 Using where
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t2 ALL a NULL NULL NULL 2
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t1 ALL a NULL NULL NULL 4 Using where
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explain select * from t1,t2 force index(a) where t1.a=t2.a;
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table type possible_keys key key_len ref rows Extra
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t2 ALL a NULL NULL NULL 2
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t1 ALL a NULL NULL NULL 5 Using where
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t1 ALL a NULL NULL NULL 4 Using where
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explain select * from t1 force index(a),t2 force index(a) where t1.a=t2.a;
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table type possible_keys key key_len ref rows Extra
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t2 ALL a NULL NULL NULL 2
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@ -351,8 +351,8 @@ t2 ALL b NULL NULL NULL 2
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t1 ref b b 5 t2.b 1 Using where
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explain select * from t1,t2 force index(c) where t1.a=t2.a;
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table type possible_keys key key_len ref rows Extra
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t1 ALL a NULL NULL NULL 5
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t2 ALL NULL NULL NULL NULL 2 Using where
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t2 ALL NULL NULL NULL NULL 2
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t1 ALL a NULL NULL NULL 4 Using where
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explain select * from t1 where a=0 or a=2;
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table type possible_keys key key_len ref rows Extra
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t1 ALL a NULL NULL NULL 5 Using where
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@ -307,17 +307,17 @@ table type possible_keys key key_len ref rows Extra
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t1 range a a 9 NULL 8 Using where; Using index
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explain select * from t1 where a = 2 and b >0 order by a desc,b desc;
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table type possible_keys key key_len ref rows Extra
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t1 range a a 9 NULL 5 Using where; Using index
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t1 range a a 9 NULL 4 Using where; Using index
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explain select * from t1 where a = 2 and b is null order by a desc,b desc;
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table type possible_keys key key_len ref rows Extra
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t1 ref a a 9 const,const 1 Using where; Using index; Using filesort
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explain select * from t1 where a = 2 and (b is null or b > 0) order by a
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desc,b desc;
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table type possible_keys key key_len ref rows Extra
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t1 range a a 9 NULL 6 Using where; Using index
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t1 range a a 9 NULL 5 Using where; Using index
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explain select * from t1 where a = 2 and b > 0 order by a desc,b desc;
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table type possible_keys key key_len ref rows Extra
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t1 range a a 9 NULL 5 Using where; Using index
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t1 range a a 9 NULL 4 Using where; Using index
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explain select * from t1 where a = 2 and b < 2 order by a desc,b desc;
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table type possible_keys key key_len ref rows Extra
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t1 range a a 9 NULL 2 Using where; Using index
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@ -1,6 +1,6 @@
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drop table if exists t1;
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SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
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create table t1 (a int auto_increment primary key, b char(20));
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create table t1 (a int auto_increment primary key, b char(20), key(b));
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insert into t1 values(1,"test");
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SELECT SQL_BUFFER_RESULT * from t1;
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a b
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@ -13,7 +13,7 @@ a b
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1 test
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2 test2
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update t1 set b="a" where a=1;
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select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
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select 1 from t1,t1 as t2,t1 as t3;
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1
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1
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1
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@ -22,11 +22,9 @@ select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
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update t1 set b="a";
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You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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update t1 set b="a" where b="test";
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You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1;
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You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1 where b="test";
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You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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delete from t1 where a+0=1;
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You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
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select 1 from t1,t1 as t2,t1 as t3,t1 as t4,t1 as t5;
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@ -59,5 +57,22 @@ a b
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2 test2
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4 a
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5 a
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SELECT @@MAX_SEEKS_FOR_KEY;
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@@max_seeks_for_key
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4294967295
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analyze table t1;
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Table Op Msg_type Msg_text
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test.t1 analyze status OK
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insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
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explain select * from t1,t1 as t2 where t1.b=t2.b;
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table type possible_keys key key_len ref rows Extra
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t1 ALL b NULL NULL NULL 21
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t2 ALL b NULL NULL NULL 16 Using where
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set MAX_SEEKS_FOR_KEY=1;
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explain select * from t1,t1 as t2 where t1.b=t2.b;
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table type possible_keys key key_len ref rows Extra
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t1 ALL b NULL NULL NULL 21
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t2 ref b b 21 t1.b 6 Using where
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SET MAX_SEEKS_FOR_KEY=DEFAULT;
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drop table t1;
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SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;
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@ -60,7 +60,7 @@ drop table t1;
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#
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CREATE TABLE t1 (a int(10) unsigned not null primary key,b int(10) unsigned);
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INSERT INTO t1 VALUES (1,1),(2,1);
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INSERT INTO t1 VALUES (1,1),(2,1),(3,1),(4,1);
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CREATE TABLE t2 (a int(10) unsigned not null, key (A));
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INSERT INTO t2 VALUES (1),(2);
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CREATE TABLE t3 (a int(10) unsigned, key(A), b text);
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@ -98,10 +98,7 @@ CREATE TABLE t2 (
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INSERT INTO t2 VALUES (3,2,11,12,5400,7800);
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INSERT INTO t2 VALUES (4,2,25,12,6500,11200);
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INSERT INTO t2 VALUES (5,1,37,6,10000,12000);
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select a.id, b.category as catid, b.state as stateid, b.county as
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countyid from t1 a, t2 b where (a.token =
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'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
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select a.id, b.category as catid, b.state as stateid, b.county as countyid from t1 a, t2 b ignore index (primary) where (a.token ='a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id);
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select a.id, b.category as catid, b.state as stateid, b.county as
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countyid from t1 a, t2 b where (a.token =
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'a71250b7ed780f6ef3185bfffe027983') and (a.count = b.id) order by a.id;
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@ -4,7 +4,7 @@
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drop table if exists t1;
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SET SQL_SAFE_UPDATES=1,SQL_SELECT_LIMIT=4, SQL_MAX_JOIN_SIZE=9;
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create table t1 (a int auto_increment primary key, b char(20));
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create table t1 (a int auto_increment primary key, b char(20), key(b));
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insert into t1 values(1,"test");
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SELECT SQL_BUFFER_RESULT * from t1;
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update t1 set b="a" where a=1;
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@ -12,7 +12,7 @@ delete from t1 where a=1;
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insert into t1 values(1,"test"),(2,"test2");
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SELECT SQL_BUFFER_RESULT * from t1;
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update t1 set b="a" where a=1;
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select 1 from t1,t1 as t2,t1 as t3,t1 as t4;
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select 1 from t1,t1 as t2,t1 as t3;
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# The following should give errors:
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--error 1175
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@ -49,6 +49,17 @@ SELECT * from t1;
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SET MAX_JOIN_SIZE=DEFAULT;
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SELECT * from t1;
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#
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# Test MAX_SEEKS_FOR_KEY
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#
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SELECT @@MAX_SEEKS_FOR_KEY;
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analyze table t1;
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insert into t1 values (null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a"),(null,"a");
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explain select * from t1,t1 as t2 where t1.b=t2.b;
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set MAX_SEEKS_FOR_KEY=1;
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explain select * from t1,t1 as t2 where t1.b=t2.b;
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SET MAX_SEEKS_FOR_KEY=DEFAULT;
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drop table t1;
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SET SQL_SAFE_UPDATES=0,SQL_SELECT_LIMIT=DEFAULT, SQL_MAX_JOIN_SIZE=DEFAULT;
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@ -184,40 +184,41 @@ class handler :public Sql_alloc
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{
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protected:
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struct st_table *table; /* The table definition */
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uint active_index;
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public:
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byte *ref; /* Pointer to current row */
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byte *dupp_ref; /* Pointer to dupp row */
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uint ref_length; /* Length of ref (1-8 or the clustered
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key length) */
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uint block_size; /* index block size */
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ha_rows records; /* Records i datafilen */
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ha_rows deleted; /* Deleted records */
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ulonglong data_file_length; /* Length off data file */
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ulonglong max_data_file_length; /* Length off data file */
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ulonglong index_file_length;
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ulonglong max_index_file_length;
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ulonglong delete_length; /* Free bytes */
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ulonglong auto_increment_value;
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uint raid_type,raid_chunks;
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ha_rows records; /* Records in table */
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ha_rows deleted; /* Deleted records */
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ulong raid_chunksize;
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uint errkey; /* Last dup key */
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uint sortkey, key_used_on_scan;
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ulong mean_rec_length; /* physical reclength */
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time_t create_time; /* When table was created */
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time_t check_time;
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time_t update_time;
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ulong mean_rec_length; /* physical reclength */
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uint errkey; /* Last dup key */
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uint sortkey, key_used_on_scan;
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uint active_index;
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/* Length of ref (1-8 or the clustered key length) */
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uint ref_length;
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uint block_size; /* index block size */
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uint raid_type,raid_chunks;
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FT_INFO *ft_handler;
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bool auto_increment_column_changed;
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handler(TABLE *table_arg) : table(table_arg),active_index(MAX_REF_PARTS),
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ref(0),ref_length(sizeof(my_off_t)), block_size(0),records(0),deleted(0),
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data_file_length(0), max_data_file_length(0), index_file_length(0),
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delete_length(0), auto_increment_value(0), raid_type(0),
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key_used_on_scan(MAX_KEY),
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create_time(0), check_time(0), update_time(0), mean_rec_length(0),
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ft_handler(0)
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handler(TABLE *table_arg) :table(table_arg),
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ref(0), data_file_length(0), max_data_file_length(0), index_file_length(0),
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delete_length(0), auto_increment_value(0),
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records(0), deleted(0), mean_rec_length(0),
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create_time(0), check_time(0), update_time(0),
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key_used_on_scan(MAX_KEY), active_index(MAX_REF_PARTS),
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ref_length(sizeof(my_off_t)), block_size(0),
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raid_type(0), ft_handler(0)
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{}
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virtual ~handler(void) {}
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int ha_open(const char *name, int mode, int test_if_locked);
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@ -227,7 +228,7 @@ public:
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uint get_dup_key(int error);
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void change_table_ptr(TABLE *table_arg) { table=table_arg; }
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virtual double scan_time()
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{ return ulonglong2double(data_file_length) / IO_SIZE + 1; }
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{ return ulonglong2double(data_file_length) / IO_SIZE + 2; }
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virtual double read_time(uint index, uint ranges, ha_rows rows)
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{ return rows2double(ranges+rows); }
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virtual bool fast_key_read() { return 0;}
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@ -1175,8 +1175,8 @@ Item_cond::fix_fields(THD *thd,TABLE_LIST *tables)
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List_iterator<Item> li(list);
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Item *item;
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char buff[sizeof(char*)]; // Max local vars in function
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used_tables_cache=0;
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const_item_cache=0;
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not_null_tables_cache= used_tables_cache= 0;
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const_item_cache= 0;
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/*
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and_table_cache is the value that Item_cond_or() returns for
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not_null_tables()
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@ -3154,7 +3154,7 @@ enum options {
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OPT_MAX_BINLOG_CACHE_SIZE, OPT_MAX_BINLOG_SIZE,
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OPT_MAX_CONNECTIONS, OPT_MAX_CONNECT_ERRORS,
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OPT_MAX_DELAYED_THREADS, OPT_MAX_HEP_TABLE_SIZE,
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OPT_MAX_JOIN_SIZE, OPT_MAX_SORT_LENGTH,
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OPT_MAX_JOIN_SIZE, OPT_MAX_SORT_LENGTH, OPT_MAX_SEEKS_FOR_KEY,
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OPT_MAX_TMP_TABLES, OPT_MAX_USER_CONNECTIONS,
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OPT_MAX_WRITE_LOCK_COUNT, OPT_BULK_INSERT_BUFFER_SIZE,
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OPT_MYISAM_BLOCK_SIZE, OPT_MYISAM_MAX_EXTRA_SORT_FILE_SIZE,
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@ -3832,6 +3832,11 @@ replicating a LOAD DATA INFILE command",
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(gptr*) &global_system_variables.max_join_size,
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(gptr*) &max_system_variables.max_join_size, 0, GET_HA_ROWS, REQUIRED_ARG,
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~0L, 1, ~0L, 0, 1, 0},
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{ "max_seeks_for_key", OPT_MAX_SEEKS_FOR_KEY,
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"Limit assumed max number of seeks when looking up rows based on a key",
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(gptr*) &global_system_variables.max_seeks_for_key,
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(gptr*) &max_system_variables.max_seeks_for_key, 0, GET_ULONG,
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REQUIRED_ARG, ~0L, 1, ~0L, 0, 1, 0 },
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{"max_sort_length", OPT_MAX_SORT_LENGTH,
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"The number of bytes to use when sorting BLOB or TEXT values (only the first max_sort_length bytes of each value are used; the rest are ignored).",
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(gptr*) &global_system_variables.max_sort_length,
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@ -154,6 +154,8 @@ sys_var_thd_ulong sys_max_heap_table_size("max_heap_table_size",
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sys_var_thd_ha_rows sys_max_join_size("max_join_size",
|
||||
&SV::max_join_size,
|
||||
fix_max_join_size);
|
||||
sys_var_thd_ulong sys_max_seeks_for_key("max_seeks_for_key",
|
||||
&SV::max_seeks_for_key);
|
||||
#ifndef TO_BE_DELETED /* Alias for max_join_size */
|
||||
sys_var_thd_ha_rows sys_sql_max_join_size("sql_max_join_size",
|
||||
&SV::max_join_size,
|
||||
@ -348,6 +350,7 @@ sys_var *sys_variables[]=
|
||||
&sys_max_delayed_threads,
|
||||
&sys_max_heap_table_size,
|
||||
&sys_max_join_size,
|
||||
&sys_max_seeks_for_key,
|
||||
&sys_max_sort_length,
|
||||
&sys_max_tmp_tables,
|
||||
&sys_max_user_connections,
|
||||
@ -492,6 +495,7 @@ struct show_var_st init_vars[]= {
|
||||
{sys_max_delayed_threads.name,(char*) &sys_max_delayed_threads, SHOW_SYS},
|
||||
{sys_max_heap_table_size.name,(char*) &sys_max_heap_table_size, SHOW_SYS},
|
||||
{sys_max_join_size.name, (char*) &sys_max_join_size, SHOW_SYS},
|
||||
{sys_max_seeks_for_key.name, (char*) &sys_max_seeks_for_key, SHOW_SYS},
|
||||
{sys_max_sort_length.name, (char*) &sys_max_sort_length, SHOW_SYS},
|
||||
{sys_max_user_connections.name,(char*) &sys_max_user_connections, SHOW_SYS},
|
||||
{sys_max_tmp_tables.name, (char*) &sys_max_tmp_tables, SHOW_SYS},
|
||||
|
@ -310,6 +310,7 @@ struct system_variables
|
||||
ulong tx_isolation;
|
||||
ulong table_type;
|
||||
ulong default_week_format;
|
||||
ulong max_seeks_for_key;
|
||||
|
||||
my_bool log_warnings;
|
||||
my_bool low_priority_updates;
|
||||
|
@ -1271,14 +1271,14 @@ make_join_statistics(JOIN *join,TABLE_LIST *tables,COND *conds,
|
||||
|
||||
/*
|
||||
Set a max range of how many seeks we can expect when using keys
|
||||
This was (s->read_time*5), but this was too low with small rows
|
||||
This is can't be to high as otherwise we are likely to use
|
||||
table scan.
|
||||
*/
|
||||
s->worst_seeks= (double) s->found_records / 5;
|
||||
s->worst_seeks= min((double) s->found_records / 10,
|
||||
(double) s->read_time*3);
|
||||
if (s->worst_seeks < 2.0) // Fix for small tables
|
||||
s->worst_seeks=2.0;
|
||||
|
||||
/* if (s->type == JT_EQ_REF)
|
||||
continue; */
|
||||
if (s->const_keys)
|
||||
{
|
||||
ha_rows records;
|
||||
@ -1884,6 +1884,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
best=best_time=records=DBL_MAX;
|
||||
KEYUSE *best_key=0;
|
||||
uint best_max_key_part=0;
|
||||
my_bool found_constrain= 0;
|
||||
|
||||
if (s->keyuse)
|
||||
{ /* Use key if possible */
|
||||
@ -1964,6 +1965,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
}
|
||||
else
|
||||
{
|
||||
found_constrain= 1;
|
||||
/*
|
||||
Check if we found full key
|
||||
*/
|
||||
@ -2000,16 +2002,18 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
records=2.0; // Can't be as good as a unique
|
||||
}
|
||||
}
|
||||
/* Limit the number of matched rows */
|
||||
tmp= records;
|
||||
set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
|
||||
if (table->used_keys & ((key_map) 1 << key))
|
||||
{
|
||||
/* we can use only index tree */
|
||||
uint keys_per_block= table->file->block_size/2/
|
||||
(keyinfo->key_length+table->file->ref_length)+1;
|
||||
tmp=(record_count*(records+keys_per_block-1)/
|
||||
keys_per_block);
|
||||
tmp=record_count*(tmp+keys_per_block-1)/keys_per_block;
|
||||
}
|
||||
else
|
||||
tmp=record_count*min(records,s->worst_seeks);
|
||||
tmp=record_count*min(tmp,s->worst_seeks);
|
||||
}
|
||||
}
|
||||
else
|
||||
@ -2039,7 +2043,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
{
|
||||
/*
|
||||
Assume that the first key part matches 1% of the file
|
||||
and that the hole key matches 10 (dupplicates) or 1
|
||||
and that the hole key matches 10 (duplicates) or 1
|
||||
(unique) records.
|
||||
Assume also that more key matches proportionally more
|
||||
records
|
||||
@ -2071,6 +2075,8 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
records=(ulong) tmp;
|
||||
}
|
||||
}
|
||||
/* Limit the number of matched rows */
|
||||
set_if_smaller(tmp, (double) thd->variables.max_seeks_for_key);
|
||||
if (table->used_keys & ((key_map) 1 << key))
|
||||
{
|
||||
/* we can use only index tree */
|
||||
@ -2113,20 +2119,31 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
s->table->used_keys && best_key) &&
|
||||
!(s->table->force_index && best_key))
|
||||
{ // Check full join
|
||||
ha_rows rnd_records= s->found_records;
|
||||
if (s->on_expr)
|
||||
{
|
||||
tmp=rows2double(s->found_records); // Can't use read cache
|
||||
tmp=rows2double(rnd_records); // Can't use read cache
|
||||
}
|
||||
else
|
||||
{
|
||||
tmp=(double) s->read_time;
|
||||
/* Calculate time to read through cache */
|
||||
/* Calculate time to read previous rows through cache */
|
||||
tmp*=(1.0+floor((double) cache_record_length(join,idx)*
|
||||
record_count /
|
||||
(double) thd->variables.join_buff_size));
|
||||
}
|
||||
|
||||
/*
|
||||
If there is a restriction on the table, assume that 25% of the
|
||||
rows can be skipped on next part.
|
||||
This is to force tables that this table depends on before this
|
||||
table
|
||||
*/
|
||||
if (found_constrain)
|
||||
rnd_records-= rnd_records/4;
|
||||
|
||||
if (best == DBL_MAX ||
|
||||
(tmp + record_count/(double) TIME_FOR_COMPARE*s->found_records <
|
||||
(tmp + record_count/(double) TIME_FOR_COMPARE*rnd_records <
|
||||
best + record_count/(double) TIME_FOR_COMPARE*records))
|
||||
{
|
||||
/*
|
||||
@ -2134,7 +2151,7 @@ find_best(JOIN *join,table_map rest_tables,uint idx,double record_count,
|
||||
will ensure that this will be used
|
||||
*/
|
||||
best=tmp;
|
||||
records= rows2double(s->found_records);
|
||||
records= rows2double(rnd_records);
|
||||
best_key=0;
|
||||
}
|
||||
}
|
||||
|
Loading…
x
Reference in New Issue
Block a user